3-Methyl-2-cyclopenten-1-one → 1-Tert-butyl-3-methylcyclopenta-1,3-diene

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Reaction Conditions

Reaction Steps

In a nitrogen atmosphere, dehydrated diethylether (350 ml) was added to a tert-butylmagnesium chloride/diethyl ether solution of 2.0 mol/lit. concentration (450 ml, 0.90 mol) to thereby obtain a solution. A solution of 3-methylcyclopentenone (43.7 g, 0.45 mmol) in dehydrated diethyl ether (150 ml) was dropped into the above solution while maintaining its temperature at 0° C. by cooling with ice. The mixture was agitated at room temperature for 15 hr. A solution of ammonium chloride (80.0 g, 1.50 mol) in water (350 ml) was dropped into the reaction mixture while maintaining its temperature at 0° C. by cooling with ice. Water (2500 ml) was added to the obtained solution, and agitated. An organic layer containing the reaction product was separated and washed with water. A 10% aqueous hydrochloric acid solution (82 ml) was added to the organic layer while maintaining its temperature at 0° C. by cooling with ice, and agitated at room temperature for 6 hr. The organic layer of the reaction mixture was separated, washed with water, a saturated aqueous solution of sodium hydrogencarbonate, water and a saturated aqueous solution of sodium chloride in sequence, and dried over anhydrous magnesium sulfate (drier). The drier was filtered off, and the solvent was distilled off from the filtrate. Thus, a liquid was obtained. 14.6 g of light-yellow liquid (1-tert-butyl-3-methylcyclopentadiene) was obtained by vacuum distillation (45 to 47° C./10 mmHg) of the above liquid. The analytical value thereof was as follows:

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